Teleprinter receiving apparatus



Sept. 17, 1940. R. D. SALMON 2,214,938

TELEPRINTER RECEIVING APPARATUS Filed Oct. 27, 1938 2. D. SALMON e 2 ATTOR/V Patented Sept. 17, 1940 UNITED STATES TELEPRINTER RECEIVING APPARATUS Reginald Dennis Salmon, Croydon, Surrey, England, assignor to Creed and Company Limited, Croydon, Surrey, England Application October 27, 1938, Serial No. 237,183 In Great Britain October 29, 1937 2 Claims.

This invention relates to teleprinters, in which a movable carriage is moved the space of a printed character after the printing of each charac-' ter. It has for its object to provide a back spacing mechanism of a simple kind and also one which is adapted particularly to power driven apparatus. 1 v

According to this invention the movable carriage is moved in steps through a differential gear mechanism and a function lever for back spacing acts to release a normally stationary part of said differential gear mechanism to move the carriage in the reverse direction for the spaces of one or more characters.

The invention will be described as applied to teleprinter apparatus printing in page form in which the movable carriage is moved backwards the space of one character in response to a dis-,

tinctive signal. The particular form of teleprinter apparatus chosen for illustration is that described in Specification No. 467,352, in which the movable carriage consists of a movable type basket cooperating with stationary selector members, but it is to be understood that the invention is equally applicable to apparatus in which the printing mechanism is stationary and the paper is moved.

The nature of the invention will be better understood from the following description of one embodiment thereof taken in conjunction with the accompanying drawing in which:

Fig. 1 is a vertical cross-section of a portion of a 'teleprinter as shown in Specification No. 467,352, with the invention applied thereto;

Fig. 2 is a plan view, and

Fig. 3 is a vertical cross-section on a line at right angles to that of Fig. 1.

Referring to the drawing, the movable type basket of a teleprinter is fixed to a rack I driven against the tension of a spring (not shown) by the engagement of the rack I with a toothed wheel 2 mounted on a shaft 3 as described in the above mentioned specification. The shaft 3 is driven through a differential gear mechanism described hereinafter by means of a dog clutch, one part I! of which is secured to a shaft II and the other part I 5 of which is slidably mounted on a sleeve I2 freely rotatable on the shaft I I. Fixed to the sleeve I2 is a gear wheel I3, which meshes with a worm I4 tending'to be rotated through a clutch from a constantly rotating motor driven shaft. The two parts I5 and ll of the dog clutch by which shaft I I is clutched to sleeve I 2, are normally held in engagement by means of a spring I6. As each character is printed worm I4 is rotated through a portion of a revolution in known manner and thus rotates shaft H, which, by means of a differential gearing rotates shaft 3 and gear wheel 2 to step the rack I the space of one character. vided in well known manner to disengage the parts I5 and it of the clutch when the carriage return signal is received. This allows a spring (not shown) to move the rack I and with it the shafts 3 and II until the carriage has returned to the beginning of the line.

The differential gear mechanism consists of a gear wheel 4 fixed to the shaft 3, a gear wheel I fixed to the shaft II, and gear wheels and 9. Gear wheel 5 is mounted in a bracket 6 attached to a disc 1 whilst gear wheel 9 is mounted in a bracket 26 attached to a disc 8. Discs I and 8 are fixed together and mounted to rotate freely in bearings carried by the aligned ends of shafts I I and 3. These discs are furnished with teeth around their peripheries, the teeth on the two discs being staggered, and are held stationary by the engagement therewith of a detent 34. Gear wheel 5 meshes with gear wheel 4 and gear wheel 9 which in turn meshes with gear wheel Ill.

Rotation of the worm I4 in a clockwise direction in Fig. 1 thus causes a movement of the rack I downwards through the plane of Fig. 1. It will be observed'that owing to the use of this differential gear mechanism the direction of rotation of the gear wheel I3 for letter spacing must be opposite from that of the corresponding gear wheel in the mechanism shown in Specification No. 467,352.

For the purpose of effecting back spacing, a function lever 8! is provided. This lever is selected, by a received combination of impulses,- through the tilting of a particular combination of the vanes 2|, 22, 23, 24 and 25. This lever 8| is pivoted on a rod 82 and urged towards the above mentioned vanes by a spring 83. The selection and actuation of the function lever 8| takes place in a manner similar to that described for other function levers in Specification No. 467,352. A function cam 3i and function bail 21 are provided for this purpose. The function cam 3| is mounted on the same shaft as the worm I4 though shown separately in the drawing for the sake of clearness. It is actuated through a clutch separate from the clutch actuating the worm I4.

When the function lever (H is selected it raises a lever I9 into the path of the function bail 21. The latter is secured to the function actuating lever 28 pivoted at 30 and held so that a roller A lever I8 is pro- -83, actuation of the function bail 21 by cam 3| draws lever l9 to the right in Fig. 1.

The discs 1 and 8 of the differential gear above referred to are held stationary by the engagement of a forked escapement lever 34 with the teeth on the disc 8. Movement of lever 19 to the right in Fig. 1 moves the forked lever 35 against the spring 35 and allows the discs 1 and 8 to move until the forked lever 34 engages a tooth on the upper disc 1. The carriage of the teleprinter with the rack l is being urged to its initial position and release of the discs I and 8 allows the rack l to rotate the wheel 2 until the carriage has moved back half the space of a character. During the latter half of the revolution of the function cam 3! the lever I9 is free to return to its original position, and the spring 35 is able to restore the forked lever E i to the position shown in the drawing. The discs 1 and Bare again release so that rack I can move a further half character space.

It will be clear that the normal forward movement of the carriage which is effected after printing of a character is prevented by well known means when the received combination of impulses selects a function lever. It may, however, be arranged that when the back spacing function lever 81 is selected the carriage is stepped forward one space in the same way. as if a character had been selected. In that event the teeth on the discs. 1 and 8 would be so spaced that the carriage moves backwards one space at each movement of the forked lever 34, that is a total of two spaces.

What is claimed is: g p

1. A machine telegraph comprising a movable carriage means comprising a differential gear mechanism for moving said carriage in one direction on the receipt of certain signals, a spring tending to move said carriage in the opposite direction and means operative upon the receipt of a separate distinctive signal to release for movement a normally stationary member of said differential gear mechanism to permit movement of said carriage by said spring.

2. A machine telegraph comprising a movable carriage, means comprising a differential gear mechanism for moving said carriage in steps in one direction on the receipt of certain signals, said difierential gear mechanism comprsing an escapement disc normally held stationary, an escapement lever co-operating with said disc, 2, spring tending to move said carriage in the opposite direction and means operative upon the receipt of a separate distinctive signal to move said escapement lever to permit limited movement of said disc and so permit limited movement of said carriage by said spring.

REGINALD DENNIS SALMON. 

